Abstract: Capturing the Geology Accurately in Alternative Reservoir Modeling Processes - An Example From the Etchegoin Reservoir at West Coalinga Field, California

TUCKER, KARLA, and JULIAN THORNE, Chevron Petroleum Technology Company, La Habra, CA

Reservoir models provide a communication and visualization tool for multidisciplinary reservoir management teams. The results from reservoir flow simulations, which depend on accurate reservoir models, are used to make important reservoir management decisions. Although the software used for building reservoir models is diverse, the quality of the reservoir data and interpretations that go into the software are critical to the modeling results.

The basal Etchegoin at West Coalinga was deposited in a shallow marine depositional setting. Core data and local outcrop studies suggest an estuary or back-barrier lagoon consisting of clean tidal channel sands and subtidal burrowed sands and muds. Although well spacing averages 150 meters (500 feet), interwell correlations are difficult in this heterogeneous depositional setting.

We will be comparing several work process flows for reservoir model building: a base-case using a standard work-flow, a facies based alternative, and hybrid approaches Iying between the two extremes. The base-case model was created stochastically from permeability traces derived by simple linear regression without facies information. An alternative model uses facies concepts throughout the modeling process. In this model, FaciesFinder was used to (1 ) generate permeability and facies traces (1 D modeling), (2) generate maps of facies assemblages (2D modeling) and (3) generate 3D reservoir models using facies- based conditional simulation. Hybrid approaches were used to generate 3D models utilizing facies traces from FaciesFinder and different geostatistical approaches.

AAPG Search and Discovery Article #90935©1998 AAPG Pacific Section Meeting, Ventura, California